1. Field of the Invention
This invention relates generally to fuel distribution systems for motor vehicles and more particularly, it relates to an improved integral fuel line for use in a fuel injection type of fuel distribution system for motor vehicles.
As is generally well known, in a fuel distribution system of the fuel injection type for motor vehicles there are required the use of three separate "fuel" lines. The first one of the "fuel" lines is sometimes referred to as a high pressure line which is used for delivering gasoline from a fuel storage tank (located at the rear of the motor vehicle) via a pump and a fuel rail to multi-port injectors or a throttle body (located at the front of the motor vehicle) for subsequent distribution to various cylinders of the vehicle's engine. The second one of the "fuel" lines is sometimes referred to as a low pressure or return line which is located adjacent the exit end of the fuel rail or throttle body for returning excess or unused portion of the gasoline back to the fuel tank. The third one of the "fuel" lines, as is required by environmental protection laws, is generally referred to as a vapor recovery line which is used to collect vaporized and evaporated gasoline from the "canister" area and other points adjacent the vehicle's engine and to return the same back to the fuel storage tank.
Heretofore, these three "fuel" lines have been formed by separate individual pipes or tubes of similar diameter which are joined together and routed in parallel between the front and rear of the motor vehicle. Further, such "fuel" lines are typically made of a metallic material. Such conventional "fuel" line arrangements and construction have the associated problems of corrosion due to the water formed in the "fuel" lines, diffusion of hydrocarbons through the wall thickness of the "fuel" lines into the atmosphere causing pollution, build-up of electrostatic charge on the outer surfaces of the "fuel" lines due to the flow of fuel therein against the inner walls, and occupying of a relatively large amount of space.
2. Description of the Prior Art
A prior art search directed to the subject matter of this application in the U.S. Patent and Trademark Office revealed the following U.S. Letters Patent:
______________________________________ 2,325,464 4,343,844 2,475,468 4,367,769 2,519,939 4,467,610 3,323,585 4,491,297 3,765,728 4,570,686 4,014,369 ______________________________________
In U.S. Pat. No. 2,325,464 to Clyde E. Bannister issued on July 27, 1943, there is disclosed a multipassage hose which includes an inner tube hose, an intermediate hose tube spaced from and surrounding the inner tube hose, and an outer hose tube spaced from and surrounding the intermediate hose tube. In U.S. Pat. No. 3,323,585 to Robert B. Cannon issued on June 6, 1967, there is disclosed a header structure for heat transfer apparatus which comprises a plurality of concentrically mounted and extended tubular members. U.S. Pat. No. 3,765,728 to Marco Peruglia issued on Oct. 16, 1973, discloses a piping for vehicular braking systems with brake fluid recirculation wherein the flexible pipe consists of two coaxial pipes, the inner of which is used to deliver brake fluid to a brake actuator cylinder and the outer of which formed a return flow duct from the cylinder.
In U.S. Pat. No. 4,014,369 to Adolph Kobres, Jr. issued on Oct. 29, 1977, there is shown a triple pipe low temperature pipeline arrangement wherein a low temperature liquid or hot gas is transferred through an inner pipe with the vapor or condensate return respectively being provided by an annulus between the inner pipe and a middle pipe. U.S. Pat. No. 4,467,610 to Carl E. Pearson et al. issued on Aug. 28, 1984 discloses a gas turbine fuel system wherein a manifold is formed with a double-walled construction to withstand high temperatures or fires around the combustor section and provide a secondary flow path for draining any fuel leakage from the manifold. The two walls of the manifold include an inner wall that encloses the primary fuel flow path through the fuel system. A concentric outer wall encloses the inner wall and protects the primary fuel flow path.
In U.S. Pat. No. 4,491,297 to Peter Maier et al. issued on Jan. 1, 1985, there is disclosed a three-way coupling which is joined up with a flexible pipe made up of three pipes nested in each other. U.S. Pat. No. 4,570,686 to George T. Devine issued on Feb. 18, 1986 discloses an apparatus for preventing blockage of vapor recovery hose by liquid fuel wherein the center pipe directs fuel to the nozzle with an annulus between the center pipe and the outer pipe for directing vapor flow from the nozzle. The remaining patents uncovered from the search but not specifically discussed merely show the state of the art relating to tubular assemblies and coupling members therefor and are thus considered to be only of general interest.
However, none of the prior art uncovered in the search disclosed an integral fuel line for use in a fuel injection type of fuel distribution for motor vehicles like that of the present invention. The integral fuel line includes an innermost tube defining a high pressure line, an intermediate tube defining a low pressure line and being disposed around the innermost tube, and an outer tube defining a vapor recovery line being disposed around the intermediate tube.